Does anyone really listen to movies with bass peaks at 115-118db? (1 Viewer)

[Edward J M]

Sub Calibration: Flat for music, +3 dB hot for HT. - Why?

For music I feel the sub should blend nicely and not draw attention to itself. If you can hear/notice the sub on music, it is calibrated too high IMO.

For HT, many of the bassy special effects (explosions, cave trolls falling dead, depth charges, little girls laughing and causing power outages, dragons flapping wings) are mastered at an arbitrary level. Their level relative to the rest of the sound track isn't rooted in reality to the same extent music is. So a flat calibration doesn't take on the same level of importance as it would for music IMO.

I prefer the sub level slightly aggressive for HT because it gives a "bit" more thrill to those special effects. I don't prefer the sub running obscenely hot for HT, though, because it ruins the overall presentation and overwhelms the soundtrack.

Regarding the OSHA Exposure Level chart Tom posted, you will note the required meter scale is A-Weighted, which filters sounds below 500 Hz. When you perform monitoring for noise levels, you deliberately filter out low frequencies and focus on noise in the bandwidth most damaging to human hearing, say 1000-5000 Hz. The SPL peaks generated in a HT environment are derived from the subwoofer at very low frequencies which are much more easily tolerated. A 110 dB peak at 25 Hz is thrilling; a 110 dB peak at 3000 Hz makes us run for the door with our hands covering our ears. This is what the F-M chart Tom also posted is all about.

 

[GrahamJW]

I think this would be a good thread to post this question. I have a paradigm PDR 10 rated at 27 Hz. When I play a sound wave (generated from a PC sound generation program) at 5 Hz and 10 Hz I can hear sound from the sub when turned up. I can definately feel air coming from the port in the rear. I was wondering if someone could explain why the sub would work at 5 or 10 Hz when it is rated for 27 Hz. Just curious to hear some answers from some of the HT gurus.

Cheers..John

 

[Ned]

Rating subs to some frequency number is the old, antiquated method of giving subwoofer specs. "Goes down to", "extends to x hz", etc, etc. It means absolutely nothing.

The Bag-End says it can "go down to" 10hz or something ridiculous, then you see test results and it's at a totally inaudible 60-65db. Manufacturers love to use a frequency extension number because they don't have to provide any SPL numbers along with it.

"Real" numbers are like those over at SGHT when they tested the dual SVS Ultras and measured 110db@20hz with less than 10% THD. Now that's 20hz extension.

 

[steve nn]

I find that using my port blockers works out very well. I can get mega spl in the lower regions with my three 25-31 CS+'s loaded in the same corner. Imo I think I might possibly like the 20 hz tune better also. It seems to intergrate better and there is so much feel along with the higher spl in the lower regions.

Minus to flat calibration for music and flat to +6 for HT does it for me along with some nice headroom.

( A 110 db peak at 25 Hz is thrilling)
I could not agree more.

 

[Pete Saunders]

I don't care how clean or distortion free your home theater is (and mine is to a fair degree), I wouldn't want to listen to 110 dbs of bass for any extended periods of time. Some of the more responsible speaker and sub companies ( M&K, Velodyne, etc) advise not to do this.

We are talking about sound pressure waves here. And yes the shorter wavelength mid and high frequencies can do damage faster, but I would not want to be subjected to high db low frequencies for very long either.

Regards

 

[Craig_Kg]

For HT, many of the bassy special effects (explosions, cave trolls falling dead, depth charges, little girls laughing and causing power outages, dragons flapping wings) are mastered at an arbitrary level. Their level relative to the rest of the sound track isn't rooted in reality to the same extent music is. So a flat calibration doesn't take on the same level of importance as it would for music IMO.

But both music and HT tracks are mixed in studios by experts with levels they deem appropriate. By doing the '+3db hot' thing, you are deviating from the intended mix - you might as well not calibrate the sub and just set it by ear.

 

[Tom Vodhanel]

>>>I don't care how clean or distortion free your home theater is (and mine is to a fair degree), I wouldn't want to listen to 110 dbs of bass for any extended periods of time. Some of the more responsible speaker and sub companies ( M&K, Velodyne, etc) advise not to do this.

We are talking about sound pressure waves here. And yes the shorter wavelength mid and high frequencies can do damage faster, but I would not want to be subjected to high db low frequencies for very long either.

Regards

 

[Tom Vodhanel]

>> think this would be a good thread to post this question. I have a paradigm PDR 10 rated at 27 Hz. When I play a sound wave (generated from a PC sound generation program) at 5 Hz and 10 Hz I can hear sound from the sub when turned up. I can definately feel air coming from the port in the rear. I was wondering if someone could explain why the sub would work at 5 or 10 Hz when it is rated for 27 Hz. Just curious to hear some answers from some of the HT gurus.

Cheers..John

 

[steve nn]

I use sub calibration as a reference and I have different tastes than what the intended mix is at my given listening level. What ever circumstances I have going on around me at the time will and can influence. If I were watching it at -0 I would most likely bring it down to flat.

I am also capable of dialing up the center a few clicks when MY tastes dictate. It seems as though some mixers hear better than others and I find no set db standard in the voice that comes across as it pertains to measured listening level.

 

[Nathan Porteous]

I would like to say who gives a crap how the director wanted you to hear it you want bass? turn it up. I listen to my movies at 114-118 bass peaks all the time hey the louder the better i love bass I LOVE IT the more the better. my car hits 135 in comps, boy i sure wish my ht did that ooo baby i need more more more i want soooo much i want to be blown over by bass hehe
well thats just my opinion of course.

 

[DavidVT]

Tom,

I have stood out on the flightline while a squadron of F-15 eagles raced off into the night sky, and also during the takeoff of a B-52 and U-2. Your correct in that prolonged listening to these levels WILL damage your hearing in a very short time!

I am starting to loose some hearing, not alot, but I can tell and know that it was from these exact things mentioned earlier.

But, I still love my BASS and maybe thats why I have an inherent need to have it loud as well

 

[Craig_Kg]

prolonged listening to these levels WILL damage your hearing in a very short time

wha?

 

[dave alan]

FYI:

OSHA has determined that there is no safe duration of SPL in excess of 115dBA (A weighted, thought to be closest to the human hearing curve).

They don't specify frequency range (i. e., low freqs are safer than high freqs).

Duration of 120 dBA before damage to hearing is 9 seconds.

Again, these numbers are not frequency dependent in any survey or chart or study I've seen.

To those who think 118 dBA is safe if it's 25 Hz or 'clean' or whatever, I wouldn't mind seeing the article that confirms that.

 

[MingL]

Much as I like deep bass, 120dBA is indeed unhealthy for the ears. But the weighting is also important as the weighting scale also dictates the freq.

Say a 20hz tone at 120dB unweighted is taken as an example.

Measuring this tone at C-weighting and A-weighting will give different measurement values even thou the tone is at constant absolute loudness.

Comparing

a 1khz tone at 120dB unweighted, would give us 120dBA and 120dBC (very damaging),
a 20hz tone at 120dB unweighted, would give us 70dBA and 114dBC(no where near damaging level of 115dBA)
a 16hz tone at 120dB unweighted, would give us 64dBA and 112dBC.(far away from the 115dBA)
a 25hz tone at 120dB unweighted, would give us 75dBA and 115dBC. (still very safe here)

So an ear damaging 115dBA 25hz rumble would really translate to 160dB or 156dBC. (Tom V, any such capable subs rolling out soon?)

I honestly doubt no practical amount of subs can ever generate 156dBC of loud bass. But practical loudspeakers are already potentially ear-damaging at the mid-range frequencies.

To summarise, 25hz bass only gets damaging when we measure the tone to be 120dBA. So to get an unhealthy 120dBA (or 156dBC) at 25hz, we would need >5 B4+ subs stacked to get to unhealthy levels.

Hence, bass at 90hz and below registering 115dBC on our Ratshack meters are barely reaching 95dBA. Barely harmful, I presume.

Or am I wrong?

 

[GrahamJW]

Thanks for the info Tom Vodhanel.

I am using a test sound generation software program (shareware)that I downloaded from the internet, so I am not sure how accurate it is. I have my digital out on my soundcard connected to the digital coax in on my receiver, so I can play sound from my PC to my receiver. Just wanted to ask something from one of your posts:

If you took a spectra shot of the subwoofer output at 5hz...I bet 5hz wouldn't even register. Nor would you see the 2nd harmonic (10hz), the 3rd harmonic (15hz), the fourth harmonic(20hz)...but you might start to see a lot of the 5th,6th,7th harmonics (25,30,35hz). All the harmonics are distortion btw.

Is this a general statement for a subwoofers? Just wondering

Cheers..John

 

[Tom Vodhanel]

>>>FYI:

OSHA has determined that there is no safe duration of SPL in excess of 115dBA (A weighted, thought to be closest to the human hearing curve).They don't specify frequency range (i. e., low freqs are safer than high freqs).

 

[Tom Vodhanel]

>>>Is this a general statement for a subwoofers? Just wondering

Cheers..John

 

[Lee-c]

Tom makes an interesting point about Dolby not likely recommending bass levels that would
hurt your hearing at ref. level. But on the other hand, the problem here is that we are just talking
about bass levels, but if you're watching a movie at ref. level, then you're not just getting
bass db's at 115 peaks (or higher), but all the other higher freq.'s at high as 105 db peaks.
And *those* freq.'s may well be causing harm. So this whole discussion on whether bass is
safe or not at ref. level on movies may be moot; since even if the bass isn't technically hurting
your ears, the other freq.'s probably are. Either way, your hearing is getting messed up.

So it would seem that DVD movies at ref. isn't something you can really do with any regularity,
not even counting the bass issue, without hearing damage. Unless I'm missing something.

Unless, of course, you're listening to something like deep organ music, which is exclusively bass,
then I guess you can feel free to crank it to ref and maybe even beyond.

 

[steve nn]

Lee-c that is where running our LFE on the + side comes in handy and if you have the set-up, it all comes out very plesurble to SOME listening ears. If it does not apeal to you I totally understand.

I myself cant stand/tolerate reference/-0 except bass content.

I think this Thread might rate up there with the T-shirt Thread????????

Tommy, I kind of thought you would be along by now with your 130 db B4+. Are you on vacation? Come on> Tell us what you like? :wink:

 

[ChadTR]

I agree with nathan, i had a truck that would hit in the high 140's at comps and I listened to that all day. I also have a cerwin vega stroker 15" in custom cabinet that does an unbelievable job as my sub, while my friend had four of them in a suburban he hit 161 at a comp.